This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We hypothesize that vitamin D supplementation reduced the progression of pre-diabetes [impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT)] in a dose-dependent manner compared to placebo administration. prior to resubmitting our NIH grant, we wish to obtain pilot data to determine if a) using a monthly dose of liquid vitamin D3) , we are able to raise serum 25-OHD into the upper normal range and 2) whether this effects glycemic indices, including fasting glucose levels and calculations o insulin sensitivity and insulin secretion. Aim: To treat primarily ethnic/racial minority patients with hypovitaminosis D [vitamin D levels less than 30 ni/mL] and pre-diabetes with placebo or two doses of vitamin D3 (300,000 IU of liquid Vit D on day 1 and day 30) designed to raise serum 25-Ohd into the upper normal range. Outcomes will include changes from baseline in fasting glucose levels and estimates of insulin sensitivity and insulin secretion.